As long as there have been computers, there have been devices for inputting data to computers. From punch card readers to mice to touch screens, a number of computer input devices have been employed and are in use today. With the proliferation of handheld computing devices, such as tablet PCs, personal digital assistants (PDAs), and smart phones, touch screens have become an increasingly popular form of computer input devices. Examples of computer input devices and associated computing devices are disclosed in U.S. Pat. Nos. 6,894,683, 6,952,203, 7,199,787, 7,295,191, 7,348,968, 7,479,949, 7,564,446, 7,577,924, and 7,614,008, and U.S. Patent Application Publication Nos. 2004/0046742, 2006/0022956, and 2008/0084396, the complete disclosures of which are hereby incorporated by reference.